meta_table.h

// Copyright (c) 2009 The Chromium Authors. All rights reserved.// Use of this source code is governed by a BSD-style license that can be// found in the LICENSE file.#ifndef APP_SQL_META_TABLE_H_#define APP_SQL_META_TABLE_H_#include <string>#include "base/basictypes.h"namespace sql {
class Connection;
class Statement;
class MetaTable {
public:
// Returns true if the 'meta' table exists.staticbool DoesTableExist(Connection* db);
MetaTable();
~MetaTable();
// Initializes the MetaTableHelper, creating the meta table if necessary. For// new tables, it will initialize the version number to |version| and the// compatible version number to |compatible_version|.bool Init(Connection* db, int version, int compatible_version);
// The version number of the database. This should be the version number of// the creator of the file. The version number will be 0 if there is no// previously set version number.//// See also Get/SetCompatibleVersionNumber().void SetVersionNumber(int version);
int GetVersionNumber();
// The compatible version number is the lowest version of the code that this// database can be read by. If there are minor changes or additions, old// versions of the code can still work with the database without failing.//// For example, if an optional column is added to a table in version 3, the// new code will set the version to 3, and the compatible version to 2, since// the code expecting version 2 databases can still read and write the table.//// Rule of thumb: check the version number when you're upgrading, but check// the compatible version number to see if you can read the file at all. If// it's larger than you code is expecting, fail.//// The compatible version number will be 0 if there is no previously set// compatible version number.void SetCompatibleVersionNumber(int version);
int GetCompatibleVersionNumber();
// Set the given arbitrary key with the given data. Returns true on success.bool SetValue(constchar* key, const std::string& value);
bool SetValue(constchar* key, int value);
bool SetValue(constchar* key, int64 value);
// Retrieves the value associated with the given key. This will use sqlite's// type conversion rules. It will return true on success.bool GetValue(constchar* key, std::string* value);
bool GetValue(constchar* key, int* value);
bool GetValue(constchar* key, int64* value);
private:
// Conveniences to prepare the two types of statements used by// MetaTableHelper.bool PrepareSetStatement(Statement* statement, constchar* key);
bool PrepareGetStatement(Statement* statement, constchar* key);
Connection* db_;
DISALLOW_COPY_AND_ASSIGN(MetaTable);
};
} // namespace sql#endif // APP_SQL_META_TABLE_H_